plastic pipe, adelite pipe that's susceptible to cracking. which is what happened in san bernardino. >> the materials are a lot better currently than they were back in the 50s, 60s and 70s. over time technology gets better. the materials gets better. >> reporter: the utility knows that customers have been shaken by the past incidents. >> it's one thing to say it, another thing is to take action. and what we want our customers to see is the action we're taking. >> we reporting live, i'm consumer editor tom vacar, ktvu channel 2 news. fire investigators tonight are still trying to figure out what sparked a fire in a home in concord that was under construction.